Technical Abstract:
Genetic variation is the raw material for selection to work on, natural selection in wild populations and artificial selection in captive populations. Within captive populations genetic variation is expected to decline over time. Because of the high fecundity of many fish species relatively few parents are required to generate the numbers of offspring needed, and the numbers of parental fish necessary to prevent the erosion of genetic diversity is high compared to the numbers often used in captive populations. Furthermore, one objective of selective breeding is to improve performance by removing individuals with poor performance, which causes genetic variation to decline. At NCCCWA we are beginning a broodstock program with three strains of rainbow trout. We want to maximize the genetic variation present at the outset of our breeding program while starting with populations that have already undergone significant improvement and domestication selection. The strains were obtained from the Clear Springs Foods, Inc. in Buhl, Idaho; TroutLodge, Inc. in Sumner, Washington; and University of Washington, in Seattle, Washington. These strains have been isolated from each other and reared in captivity for a minimum of 20 years (for the Clear Springs and UW stocks, closer to 50 and 60 years respectively). Samples of these three populations were genotyped at 9 microsatellite loci. Heterozygosity ranged from 42% to 96% and averaged 71% over all loci and populations. Each population contributed unique alleles and therefore to the genetic diversity and variation. These microsatellites markers will help to track strain identity of the broodstock.